Milkweed, Asclepias sp. , near Mount Vernon, Iowa. As you can see, the flower is very complex; the family (Asclepiadaceae) has the most highly developed floral structures amongst the dicotyledons. The seeds have characteristic plumes which aid wind dispersal; the fibres are too brittle to spin but they have been used as a substitute for kapok. The milkweeds contain chemical toxins which accumulate in the tissues of a number of animal species who regularly eat these plants. For instance, the monarch butterfly is highly unpalatable to most predators as a result of toxins obtained from its foodplant, A. syrica.